U.S. patent application number 13/531041 was filed with the patent office on 2012-10-18 for access network selection method.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Shinichiro AIKAWA, Yuichiro HAMANO, Akishige NODA.
Application Number | 20120263114 13/531041 |
Document ID | / |
Family ID | 37942449 |
Filed Date | 2012-10-18 |
United States Patent
Application |
20120263114 |
Kind Code |
A1 |
HAMANO; Yuichiro ; et
al. |
October 18, 2012 |
Access Network Selection Method
Abstract
An access network selection method in a communications network
having access networks is disclosed that includes notifying devices
in calling-side and called-side networks of the identifiers of
currently available access networks and user preferences; making a
list of candidates for an access network to be assigned to the
called-side terminal, and transmitting the list to the device in
the calling-side network; determining an access network to be
assigned to the calling-side terminal in response to reception of
the list, and notifying the calling-side terminal of the determined
access network; notifying the device in the called-side network of
the type of the access network assigned to the calling-side
terminal; and determining the access network to be assigned to the
called-side terminal in response to reception of the signal of the
type of the access network assigned to the calling-side terminal,
and notifying the called-side terminal of the determined access
network.
Inventors: |
HAMANO; Yuichiro; (Kawasaki,
JP) ; AIKAWA; Shinichiro; (Kawasaki, JP) ;
NODA; Akishige; (Kawasaki, JP) |
Assignee: |
FUJITSU LIMITED
Kawasaki-shi
JP
|
Family ID: |
37942449 |
Appl. No.: |
13/531041 |
Filed: |
June 22, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12078053 |
Mar 26, 2008 |
8238964 |
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13531041 |
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PCT/JP2006/306175 |
Mar 27, 2006 |
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12078053 |
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Current U.S.
Class: |
370/328 |
Current CPC
Class: |
H04W 88/06 20130101;
H04W 48/18 20130101; H04W 8/02 20130101 |
Class at
Publication: |
370/328 |
International
Class: |
H04W 4/00 20090101
H04W004/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 2005 |
JP |
PCT/JP2005/018921 |
Claims
1. An access network selection method in a communications network
where multiple operators have respective networks and each of the
networks includes multiple access networks, the access network
selection method comprising: transmitting a signal of a call
originating request including a service type to a called-side
terminal by a calling-side terminal; selecting a visited network
available to the called-side terminal among the networks managed by
the different operators in accordance with the service type,
including the selection result in the call originating request, and
transmitting the call originating request to the called-side
terminal by a home network of the called-side terminal having
received the call originating request; notifying a device in the
called-side visited network of an identifier of an available one or
more of the access networks in the selected visited network and a
user preference by the called-side terminal having received the
call originating request; transmitting a list of candidates for an
access network to be assigned to the called-side terminal to a
device in a calling-side network by the device in the called-side
visited network; selecting one of multiple visited networks
available to the calling-side terminal in accordance with the
service type and notifying the calling-side 2 terminal of the
selection result by a home network of the calling-side terminal
having received the list; notifying a device in the calling-side
visited network of an identifier of an available one or more of the
access networks in the selected one of the visited networks and a
user preference by the calling-side terminal having received the
selection result; determining an access network to be assigned to
the calling-side terminal and notifying a called-side network of
the determined access network by the device in the calling-side
visited network; determining the access network to be assigned to
the called-side terminal and notifying the called-side terminal of
the determined access network by the device in the called-side
visited network; notifying the calling-side terminal of the access
network assigned to the called-side terminal by one of the
called-side terminal and the device in the called-side visited
network; determining the access network to be assigned to the
calling-side terminal and notifying the calling-side terminal of
the determined access network by the device in the calling-side
visited network; and notifying the called-side terminal of a type
of the access network assigned to the calling-side terminal by one
of the calling-side terminal and the device in the calling-side
visited network.
2. The access network selection method as claimed in claim 1,
wherein the access networks have identifiers serving as addresses
for transferring user data in the access networks.
3. The access network selection method as claimed in claim 1,
wherein the access networks have identifiers including information
different from addresses for transferring user data in the access
networks.
4. An access network selection method in a communications network
where multiple operators have respective networks and each of the
networks includes multiple access networks, the access network
selection method comprising: transmitting a signal of a call
originating request including a service type to a called-side
terminal by a calling-side terminal; transmitting the signal of the
call originating request to the called-side terminal from multiple
visited networks available to the called-side terminal among the
networks managed by the different operators by a home network of
the called-side terminal having received the call originating
request; notifying each of devices in the corresponding called-side
visited networks of an identifier of an available one or more of
the access networks with respect to each of the visited networks
and a user preference by the called-side terminal having received
the call originating request; transmitting a list of candidates for
an access network to be assigned to the called-side terminal to a
home network of the called-side terminal by each of the devices in
the called-side visited networks; creating a list of multiple
access networks available to the called-side terminal based on the
lists and transmitting the list to a home network of the
calling-side terminal by the home network of the called-side
terminal; transmitting the list to the calling-side terminal
through multiple visited networks available to the calling-side
terminal by the home network of the calling-side terminal having
received the list; notifying each of devices in the corresponding
calling-side visited networks of an identifier of an available one
or more of the access networks with respect to each of the visited
networks and a user preference by the calling-side terminal having
received the list; transmitting a list of candidates for an access
network to be assigned to the calling-side terminal to the home
network of the calling-side terminal by each of the devices in the
calling-side visited networks; creating a list of multiple access
networks available to the calling-side terminal based on the lists
and transmitting the list to the home network of the called-side
terminal by the home network of the calling-side terminal;
selecting a visited network to be assigned to the called-side
terminal and notifying the selected visited network of the
selection by the home network of the called-side terminal;
determining the access network to be assigned to the called-side
terminal and notifying the called-side terminal of the determined
access network by the device in the called-side visited network;
notifying the calling-side terminal of the access network assigned
to the called-side terminal by one of the called-side terminal and
the device in the called-side visited network; selecting a visited
network to be assigned to the calling-side terminal and notifying
the selected visited network of the selection by the home network
of the calling-side terminal; determining the access network to be
assigned to the calling-side terminal and notifying the
calling-side terminal of the determined access network by the
device in the calling-side visited network; and notifying the
called-side terminal of a type of the access network assigned to
the calling-side terminal by one of the calling-side terminal and
the device in the calling-side visited network.
5. An access network selection method in a communications network
where multiple operators have respective networks and each of the
networks includes multiple access networks, the access network
selection method comprising: transmitting a signal of a call
originating request including a service type to a called-side
terminal by a calling-side terminal; transmitting the signal of the
call originating request to the called-side terminal through one or
more visited networks available to the called-side terminal among
the networks managed by the different operators by a home network
of the called-side terminal having received the call originating
request; notifying each of devices in the corresponding called-side
visited networks of an identifier of an available one or more of
the access networks with respect to each of the visited networks
and a user preference by the called-side terminal having received
the call originating request; transmitting a list of candidates for
an access network to be assigned to the called-side terminal to the
home network of the called-side terminal by each of the devices in
the called-side visited networks; creating a list of multiple
access networks available to the called-side terminal based on the
lists and transmitting the list to a home network of the
calling-side terminal by the home network of the called-side
terminal; transmitting the list to the calling-side terminal
through multiple visited networks available to the calling-side
terminal by the home network of the calling-side terminal;
notifying each of devices in the corresponding calling-side visited
networks of an identifier of an available one or more of the access
networks with respect to each of the visited networks and a user
preference by the calling-side terminal; transmitting a list of
candidates for an access network to be assigned to the calling-side
terminal to the home network of the calling-side terminal by each
of the devices in the calling-side visited networks; creating a
list of multiple access networks available to the calling-side
terminal based on the lists and transmitting the list to the home
network of the called-side terminal by the home network of the
calling-side terminal; selecting a visited network and the access
network to be assigned to the called-side terminal and notifying
the called-side terminal of the selected visited network and access
network by the home network of the called-side terminal; notifying
the calling-side terminal of the access network assigned to the
called-side terminal by one of the called-side terminal and the
device in the called-side visited network; selecting a visited
network and the access network to be assigned to the calling-side
terminal and notifying the calling-side terminal of the selected
visited network and access network by the home network of the
calling-side terminal; and notifying the called-side terminal of
the access network assigned to the calling-side terminal by one of
the calling-side terminal and the device in the calling-side
visited network.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/078,053, filed Mar. 26, 2008, now U.S. Pat.
No. ______, which is a continuation application filed under 35
U.S.C. 111(a) claiming benefit under 35 U.S.C. 120 and 365(c) of
PCT International Application No. PCT/JP2006/306175, filed on Mar.
27, 2006, which claims priority to PCT International Application
No. PCT/JP2005/018921, filed on Oct. 14, 2005. The entire contents
of the foregoing applications are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of selecting an
access network in accordance with a service provided, a user
preference, or an operator policy in a communications network where
multiple access networks are available.
[0004] 2. Description of the Related Art
[0005] 3GPP (Third Generation Partnership Protocol) technical
specifications TS 23.122 v6.5.0 (2005.06) define a method of
performing location registration through selection of an optimum
network from combinations of operators' networks and access
networks by a user or terminal.
[0006] According to the specifications, however, communications are
always performed through the network on which the location
registration has been performed, irrespective of the type of a
service that the user wishes to use (for example, voice
communications, data reception, etc.). Therefore, there is a
problem in that even if there is another optimum network for the
service that the user (terminal) wishes to use and the location of
the
user allows the user to use the network, the user can only use the
network on which the user has performed location registration.
[0007] Further, there is also a problem in that the availability of
resources on the network side, an operator policy, and the type of
a network selected by a correspondent, which should be determined
at the start of the communications, are not taken into
consideration in selecting a network because the network selection
is performed at the time of location registration by the terminal
alone.
[0008] As the same idea as described above, Patent Document 1
discloses a method of determining which access network to connect
to in a location where multiple access means (W-CDMA and WLAN,
etc.) are available. However, the method described in Patent
Document 1 also shows that a terminal selects an optimum one from
multiple access networks, thus having the same problems as the
above-described technical specifications TS 23.122.
[0009] On the other hand, Patent Document 2 proposes a method of
selecting an optimum access network based on the resource
information of each of multiple access networks by a common radio
resource manager in a network. However, this proposal has a problem
in that while the resource conditions of the access networks and an
operator preference are considered, the preference of a user or
terminal or the result of selection of an access network by a
correspondent is not considered.
[0010] Further, Patent Document 3 discloses a method of performing
handover from an access network to another access network at a
location where multiple access means (W-CDMA and WLAN, etc.) are
available at the time of handover.
[0011] This method disclosed in Patent Document 3 shows that a
terminal selects an optimum one from multiple access networks, and
the location and moving speed of the terminal itself, cost, network
QoS (Quality of Service) information, battery consumption, etc.,
are cited as information for the terminal selecting an access
network. However, this method also has the same problem as
described above in that the result of selection of an access
network in the case of handover by a correspondent is not
considered.
[0012] In 3GPP, TS 25.401 v6.6.0 (2005.06) defines handover within
the access networks of the same type (within GERANs and within
UTRANs) and between different access networks (between GERAN and
UTRAN). Whether to perform this handover is determined by the
access network based on the information of which the access network
is notified by the terminal, such as the intensity of the radio
wave received by the terminal. Accordingly, a core network does not
intervene in this determination, so that there is a problem in that
the QoS of the entire network, an operator policy, or the type of
the access network used by a correspondent is not considered.
[0013] [Patent Document 1] Japanese Laid-Open Patent Application
No. 2005-110262 [0014] [Patent Document 2] Japanese Translation of
PCT International Application No. 2004-511988 [0015] [Patent
Document 3] Japanese Laid-Open Patent Application No.
2003-333639
[0016] As described above, conventionally, the access network used
to perform communications is fixed to the access network selected
by a terminal or used at the time of location registration even if
multiple access networks are available.
[0017] Further, in the case of selecting an optimum access network
in accordance with the resource conditions of each access network,
the access network is selected based only on the information
detectable by the terminal (user) (such as the availability of the
resources of a radio section). Therefore, a user preference such as
which network the user wishes to use or the result of selection of
an access network by a correspondent is not considered, so that
there is a problem in that an optimum access network is not
necessarily selected from the viewpoint of the entire
communication-related path.
SUMMARY OF THE INVENTION
[0018] Embodiments of the present invention may solve or reduce one
or more of the above-described problems.
[0019] According to one embodiment of the present invention, there
is provided an access network selection method in which one or more
of the above-described problems may be solved or reduced.
[0020] According to one embodiment of the present invention, there
are provided a method that makes it possible to select an optimum
access network from the viewpoint of the entire
communication-related path by defining the procedure for the
optimum access network providing information for the selection, and
a network system using the same.
[0021] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
notifying a device in a calling-side network of an identifier
corresponding to a currently available access network and a user
preference from a calling-side terminal making a call originating
request; notifying a device in a called-side network of an
identifier corresponding to a currently available access network
and a user preference from a called-side terminal having received
the call originating request via the device in the calling-side
network; making a list of candidates for an access network to be
assigned to the called-side terminal based on a predetermined
condition in response to reception of a notification signal from
the called-side terminal as a trigger, and transmitting the list
from the device in the called-side network to the device in the
calling-side network; determining an access network to be assigned
to the calling-side terminal in response to reception of the list
of the candidates for the access network to be assigned from the
device in the called-side network as a trigger, and notifying the
calling-side terminal of the determined access network by the
device in the calling-side network; notifying the device in the
called-side network of a type of the access network assigned to the
calling-side terminal by one of the calling-side terminal and the
device in the calling-side network; and determining the access
network to be assigned to the called-side terminal based on a
condition based on which the access network to be assigned to the
calling-side terminal has been determined in the device in the
calling-side terminal, in response to reception of a signal of the
type of the access network assigned to the calling-side terminal as
a trigger, and notifying the called-side terminal of the determined
access network by the device in the called-side network.
[0022] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
notifying a device in a calling-side network of an identifier
corresponding to a currently available access network and a user
preference from a calling-side terminal making a call originating
request; transmitting a provisional response signal to the call
originating request, from a called-side terminal having received
the call originating request via the device in the calling-side
network; and determining an access network to be assigned to the
calling-side terminal in response to reception of the provisional
response signal from the called-side terminal as a trigger, and
notifying the calling-side terminal of the determined access
network by the device in the calling-side network.
[0023] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
notifying a device in a calling-side network of an identifier
corresponding to a currently available access network and a user
preference from a calling-side terminal making a call originating
request; transmitting a response signal to the call originating
request, from a called-side terminal having received the call
originating request via the device in the calling-side network; and
determining an access network to be assigned to the calling-side
terminal in response to reception of the response signal from the
called-side terminal as a trigger, and notifying the calling-side
terminal of the determined access network by the device in the
calling-side network.
[0024] According to one aspect of the present invention, it is
possible to select an optimum access network from the viewpoint of
the entire communication-related path by defining the procedure for
the optimum access network providing information for the
selection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Other objects, features and advantages of the present
invention will become more apparent from the following detailed
description when read in conjunction with the accompanying
drawings, in which:
[0026] FIG. 1 is a configuration diagram of a mobile communications
network that implements the present invention;
[0027] FIG. 2A is a diagram showing a configuration corresponding
to a mobile communications terminal UE1 in a disposition of
functions for implementing the present invention;
[0028] FIG. 2B is a diagram showing a function disposition
configuration corresponding to a mobile communications terminal UE2
in the disposition of functions for implementing the present
invention;
[0029] FIG. 3 is a diagram showing a procedure for acquiring a
local home address (L-HoA) and a care-of address (CoA) and
performing registration with S-CSCF in a home network HN 1 by the
mobile communications terminal UE1;
[0030] FIG. 4A is a diagram showing an operational sequence on the
mobile communications terminal UE1 side at the start of
communications in the case where the mobile communications terminal
UE1 makes a request for communications to the mobile communications
terminal UE2;
[0031] FIG. 4B is a diagram showing an operational sequence on the
mobile communications terminal UE2 side at the start of
communications in the case where the mobile communications terminal
UE1 makes a request for communications to the mobile communications
terminal UE2;
[0032] FIG. 5A is a diagram showing an operational sequence on the
mobile communications terminal UE1 side at the start of
communications in the case where a called-side terminal and network
do not have a network selecting function;
[0033] FIG. 5B is a diagram showing an operational sequence on the
mobile communications terminal UE2 side at the start of
communications in the case where a called-side terminal and network
do not have a network selecting function;
[0034] FIG. 6A is a diagram showing an operational sequence on the
mobile communications terminal UE1 side at the start of
communications in the case where the mobile communications terminal
UE2 that is a called-side terminal directly returns a response
signal (OK) without a provisional response signal (Session
Progress);
[0035] FIG. 6B is a diagram showing an operational sequence on the
mobile communications terminal UE2 side at the start of
communications in the case where the mobile communications terminal
UE2 that is a called-side terminal directly returns a response
signal (OK) without a provisional response signal (Session
Progress);
[0036] FIG. 7A is a diagram showing an operational sequence on the
mobile communications terminal UE1 side at the start of
communications in the case where a calling-side terminal and
network do not have a network selecting function;
[0037] FIG. 7B is a diagram showing an operational sequence on the
mobile communications terminal UE2 side at the start of
communications in the case where a calling-side terminal and
network do not have a network selecting function;
[0038] FIG. 8A is a diagram showing an operational sequence on the
mobile communications terminal UE1 side at the start of
communications in the case where a calling-side terminal does not
support an acknowledgment signal (PRACK);
[0039] FIG. 8B is a diagram showing an operational sequence on the
mobile communications terminal UE2 side at the start of
communications in the case where a calling-side terminal does not
support an acknowledgment signal (PRACK);
[0040] FIG. 9 is a diagram showing a handover sequence in the case
where a mobile communications terminal UE in communication detects
an occasion to switch access networks;
[0041] FIG. 10 is a diagram showing a handover sequence in the case
where a device in the network detects an occasion;
[0042] FIG. 11 is a configuration diagram of a mobile
communications network that implements the present invention;
[0043] FIG. 12 is a diagram showing a disposition of functions that
implements the present invention;
[0044] FIG. 13A is a diagram showing a location registration
procedure;
[0045] FIG. 13B is a diagram showing the location registration
procedure;
[0046] FIG. 14A shows a calling-side sequence diagram in the case
where a home network HN statically selects only a visited network
VN and the visited network VN dynamically selects an access network
AN;
[0047] FIG. 14B shows a called-side sequence diagram in the case
where a home network HN statically selects only a visited network
VN and the visited network VN dynamically selects an access network
AN;
[0048] FIG. 15A shows a calling-side sequence diagram in the case
where a home network HN dynamically selects only a visited network
VN and the visited network VN also dynamically selects an access
network AN;
[0049] FIG. 15B shows a called-side sequence diagram in the case
where a home network HN dynamically selects only a visited network
VN and the visited network VN also dynamically selects an access
network AN;
[0050] FIG. 16A shows a calling-side sequence diagram in the case
where a home network HN statically selects a visited network VN and
an access network AN;
[0051] FIG. 16B shows a called-side sequence diagram in the case
where a home network HN statically selects a visited network VN and
an access network AN;
[0052] FIG. 17A shows a calling-side sequence diagram in the case
where a home network HN dynamically selects a visited network VN
and an access network AN;
[0053] FIG. 17B shows a called-side sequence diagram in the case
where a home network HN dynamically selects a visited network VN
and an access network AN;
[0054] FIG. 18A show a calling-side sequence diagram in the case
where a home network HN statically selects only a visited network
VN and the visited network VN statically selects an access network
AN;
[0055] FIG. 18B show a called-side sequence diagram in the case
where a home network HN statically selects only a visited network
VN and the visited network VN statically selects an access network
AN;
[0056] FIG. 19 shows a configuration diagram of a mobile
communications network implementing the present invention in the
case where there is the function of performing mobility management
between a visited network VN and access networks ANs; and
[0057] FIG. 20 is a diagram showing a location registration
procedure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0058] A description is given, with reference to the accompanying
drawings, of embodiments of the present invention.
[0059] According to one aspect of the present invention, it is
possible for a terminal to notify a device in the network of the
type of an available access network and a user preference and it is
possible for the device in the network to select an access network
at the time of originating a call and the time of receiving a call,
taking into account, in addition to these information items, a
user-requested service or application, the resource conditions in
the wired network or a radio section, an operator policy, etc.
[0060] Further, if both calling network side and called network
side have the above-described network selecting function, by newly
providing a procedure for devices in the network notifying each
other of candidates for an access network to be selected or a
selected access network, it is possible to select an access network
in the network in accordance with the candidates for the access
network to be selected or the selected access network in the
network where the correspondent exists.
[0061] Further, it is made possible to reselect an access network
and perform handover when an available access system changes with a
movement of a terminal after the start of communications or when
there is a change of the service or application requested by a user
or the resource conditions of a radio section.
[0062] Further, notifying a correspondent of the type of the
selected access network after completion of the above-described
handover makes it possible for the notified correspondent to
reselect its own access network in response to the change of the
access network in the notifying network where the correspondent
exists as a trigger.
[0063] According to one aspect of the present invention, it is
possible to implement the function of selecting an optimum access
network at the time of originating and receiving a call and during
communication without fixation to the result of selection at the
time of location registration based on various conditions as well
as a user preference in a communications network having multiple
access networks.
Embodiment 1
[0064] Shown below is an embodiment of the present invention in the
case of applying SIP (Session Initiation Protocol), which is a
communications control protocol used in IP telephony, as a protocol
in a mobile communications network.
[0065] FIG. 1 is a configuration diagram of a mobile communications
network that implements the present invention. User equipment UE1
and user equipment UE2, which are mobile communications terminals
that actually perform communications in the present invention, are
assigned home addresses (HoAs) HoA1 and HoA2 by home networks (HNs)
1 and 2 to which they subscribe, respectively.
[0066] The home network HN1 and the home network HN2 are mobile
communications networks to which the mobile communications
terminals UE1 and UE2 subscribe, respectively. Further, visited
networks (VNs) 20 and 21 are networks where the mobile
communications terminals UE1 and UE2 exist, respectively. Further,
access networks 20a and 20b are access means provided to the mobile
communications terminal UE1 by the visited network VN 20, and
access networks 21a and 21b are access means provided to the mobile
communications terminal UE2 by the visited network VN 21.
[0067] FIG. 2A shows a function configuration corresponding to the
mobile communications terminal UE1 in a disposition of functions
for implementing the present invention. FIG. 2B is a diagram
showing a function disposition configuration corresponding to the
correspondent mobile communications terminal UE2.
[0068] A description is given below of FIG. 2A, while it is the
same with FIG. 2B about the mobile communications terminal UE2.
Accordingly, a description of FIG. 2B is omitted as it is thought
proper.
[0069] In FIG. 2A and FIG. 2B, characteristic are function parts as
local home agents (L-HAs) 1-1 and 2-1 provided by the present
invention.
[0070] That is, the local home agents (L-HAs) 1-1 and 1-2 are
function parts newly provided to implement the present invention,
and have the function of assigning local home addresses (L-HoA1 and
L-HoA2) to the mobile communications terminals UE1 and UE2 that
move in a service provision area and the function of selecting an
optimum access network at the start of communications based on the
type of an available access network and a user profile transmitted
from the mobile communications terminals UE1 and UE2, QoS (Quality
of Service), and an operator policy.
[0071] The mobile communications terminals UE1 and UE2 have the
function of performing communications based on multiple radio
systems, and have the function of being assigned a care-of address
(CoA) for each corresponding radio system and a local home address
(L-HoA1, L-HoA2) in the visited network (VN) 20, 21 and storing
them.
[0072] Further, the mobile communications terminals UE1 and UE2
have the function of notifying the local home agents (L-HAs) 20-1
and 21-1, at the time of requesting to originate a call and at the
time of responding to a received call, of a care-of address (CoA)
corresponding to an available radio system (access network) at that
time, a user preference, and the local home address (L-HoA).
[0073] The procedure for acquiring a local home address (L-HoA) and
a care-of address (CoA) and performing registration with an S-CSCF
(Serving Call Session Control Function) 1-5 in the home network HN
1 by the mobile communications terminal UE1 is shown below and in
FIG. 3.
[0074] When the mobile communications terminal UE1 moves in the
service provision area of the visited network VN 20, the mobile
communications terminal UE1 acquires care-of addresses CoA1-1 and
CoA1-2 from the access networks 20a and 20b, respectively, upon
receiving their radio waves for the first time (step S1).
[0075] The mobile communications terminal UE1 registers the home
address HoA1, assigned from the home network HN 1 and serving as an
identifier, and the care-of address CoA1-1, assigned from the
access network 20a, with the local home agent (L-HA) 20-1 via the
access network 20a (step S2).
[0076] When the local home agent 20-1 accepts the registration from
the mobile communications terminal UE1, the local home agent 20-1
refers to a table that it retains, and determines whether the local
home address L-HoA1 corresponding to the home address HoA1 has been
assigned.
[0077] If no local home address L-HoA has been assigned, the local
home agent 20-1 assigns the local home address L-HoA1 to the mobile
communications terminal UE1, includes it in a response to the
registration, and transmits it to the mobile communications
terminal UE1 (step S3). At the same time, the local home agent
(L-HA) 20-1 correlates the home address HoA1 with the local home
address L-HoA1 and the care-of address CoA1-1 and stores them (step
S4).
[0078] The mobile communications terminal UE1 registers the home
address HoA1 and the care-of address CoA1-2 with the local home
agent L-HA 20-1 via the access network 20b in the same procedure
(step S5).
[0079] Since the local home agent L-HA 20-1 has already assigned
the local home address L-HoA1 to the mobile communications terminal
UE1, the local home agent L-HA 20-1 makes only a response of
registration completion to the mobile communications terminal UE1
(step S6). At the same time, the local home agent (L-HA) 20-1
correlates the home address HoA1 with the care-of address CoA1-2
and stores them (step S7).
[0080] Upon completion of registration of all the acquired care-of
addresses CoAs with the local home agent L-HA 20-1 and acquisition
of the local home address L-HoA1, the mobile communications
terminal UE1 registers the local home address L-HoA1 with the
S-CSCF 1-5 in the home network HN 1 to which it subscribes (step
S8).
[0081] By the above-described procedure, acquisition of the local
home address L-HoA and the care-of address CoA and registration
with the S-CSCF (Serving Call Session Control Function) 1-5 by the
mobile communications terminal UE are completed.
[0082] Next, an operational sequence at the start of communications
in the case where the mobile communications terminal UE1 makes a
request for communications to the mobile communications terminal
UE2 as an embodiment is shown in FIG. 4A and FIG. 4B. FIG. 4A shows
processing from the mobile communications terminal UE1 side, and
FIG. 4B shows processing from the mobile communications terminal
UE2 side. In this embodiment, the mobile communications terminal
and the network have a network selecting function on both calling
and called sides.
[0083] In FIG. 4A and FIG. 4B, the mobile communications terminal
UE1 includes the local home address L-HoA1 and the care-of
addresses CoA1-1 and CoA1-2, which are identifiers, and a user
preference 1 in a signal of a request to originate a call (Invite),
and transmits it to the local home agent L-HA 20-1 via the access
network 20a (step S10).
[0084] Here, the local home address L-HoA is used for the local
home agent L-HA to determine which mobile communications terminal
UE the communications request is from, and the care-of addresses
CoA1-1 and CoA1-2 are used for the mobile communications terminal
UE1 to notify the local home agent L-HA1 of the type of an
available access network.
[0085] Further, the user preference 1 is information for notifying
the local home agent L-HA 20-1 on what basis the user of the mobile
communications terminal UE1 wishes to have network selection
performed (for example, with priority on communications speed,
priority on communications cost, etc.).
[0086] Receiving the call originating request signal (Invite) from
the mobile communications terminal UE1, the local home agent L-HA
20-1 stores therein the local home address L-HoA1, the care-of
addresses CoA1-1 and CoA1-2, and the user preference 1 transmitted
from the mobile communications terminal UE1, and issues a call
originating request signal to the mobile communications terminal
UE2 (step S11).
[0087] In FIG. 4B, receiving the call originating request signal
(Invite), the mobile communications terminal UE2 transmits the
local home address L-HoA2, care-of addresses CoA2-1 and CoA2-2, and
a user preference 2 in a provisional response signal (Session
Progress) to the local home agent 21-1 via the access network 21a
(step S12). Here, the contents of the transmission from the mobile
communications terminal UE2 to the local home agent 21-1 are the
same as the contents of the transmission from the mobile
communications terminal UE1 to the local home agent 20-1.
[0088] Receiving the provisional response signal (Session Progress)
from the mobile communications terminal UE2, the local home agent
L-HA 21-1 stores therein the local home address L-HoA2, the care-of
addresses CoA2-1 and CoA2-2, and the user preference 2, and in
cooperation with a PDF (Policy Decision Function) 21-2, creates a
list of access networks providing services to the mobile
communications terminal UE2 in order appropriate for this
communication, taking into account QoS, an operator policy, etc.,
as well as the care-of addresses CoA2-1 and CoA2-2 and the user
preference transmitted from the mobile communications terminal UE2
(step S13).
[0089] The local home agent L-HA 21-1 includes the created access
network list in a provisional response signal (Session Progress),
and transmits it to the local home agent L-HA 20-1 (step S14).
[0090] Receiving the provisional response signal (Session Progress)
from the local home agent L-HA 2-2 of the visited network VN 21,
the local home agent L-HA 20-1 of the visited network VN 20, in
cooperation with a PDF 20-2, selects an optimum access network for
the mobile communications terminal UE1, taking into account QoS, an
operator policy, etc., as well as the access network list
transmitted from the local home agent L-HA 21-1 and the care-of
addresses CoA1-1 and CoA1-2 and the user preference transmitted
from the mobile communications terminal UE1 (step S15). In this
embodiment, the access network 20b is selected.
[0091] The local home agent L-HA 20-1 includes the selected access
network in a provisional response signal (Session Progress), and
transmits it to the mobile communications terminal UE1 (step
S16).
[0092] Receiving the provisional response signal (183 Session
Progress) from the local home agent L-HA 20-1, the mobile
communications terminal UE1 recognizes that the access network 20b
has been selected, and reserves radio resources for performing
communications via the access network 20b (step S17).
[0093] Further, the mobile communications terminal UE1 includes
information on the type of the selected access network 20b in an
acknowledgment signal (PRACK) responsive to the provisional
response signal (Session Progress), and transmits it to the local
home agent L-HA 21-1 on the called-side network 21 (step S18).
[0094] The information on the type of the selected access network
may be included in the acknowledgement signal (PRACK) and
transmitted to the local home agent L-HA 21-1 by the local home
agent L-HA 20-1 that has actually made the selection.
[0095] Receiving the acknowledgement signal (PRACK) from the mobile
communications terminal UE1, the local home agent L-HA 21-1, in
cooperation with the PDF 21-2, selects an optimum access network
for the mobile communications terminal UE2, taking into account
QoS, an operator policy, etc., as well as the selected access
network reported from the mobile communications terminal UE1 and
the care-of addresses CoA2-1 and CoA2-2 and the user preference
transmitted from the mobile communications terminal UE2 (step S19).
In this embodiment, the access network 21b is selected. The local
home agent L-HA 21-1 includes the selected access network 21b in an
acknowledgement signal (PRACK), and transmits it to the mobile
communications terminal UE2 (step S20).
[0096] Receiving the acknowledgement signal (PRACK) from the local
home agent L-HA 21-1, the mobile communications terminal UE2
recognizes that the access network 21b has been selected, and
reserves radio resources for performing communications via the
access network 21b (step S21).
[0097] Thereafter, the mobile communications terminal UE2 includes
the fact that the selected access network is the access network 21b
in a response signal (OK) to the acknowledgement signal (PRACK) and
returns it to the mobile communications terminal UE1 (step
S22).
[0098] Further, the mobile communications terminal UE2 returns a
response signal (OK) to the call originating request signal
(Invite) to the mobile communications terminal UE1 (step S23), and
the mobile communications terminal UE1 returns an acknowledgement
signal (ACK) responsive to the call originating request OK (Invite)
to the mobile communications terminal UE2 (step S24). Thereby, the
operational sequence at the start of communications is
completed.
Embodiment 2
[0099] The above-described embodiment shown in FIG. 4A and FIG. 4B
shows the case where both calling and called mobile communications
terminals UEs have a network selecting function, but there may be a
case where one of the terminals or networks does not have a network
selecting function as in the communications between a mobile
communications terminal and a fixed terminal.
[0100] An operational sequence at the start of communications in
the case where a called-side terminal and network do not have a
network selecting function is shown in FIG. 5A and FIG. 5B. The
sequence in this embodiment is different from the sequence shown in
FIG. 4A and FIG. 4B as follows.
[0101] The provisional response signal (Session Progress) from the
mobile communications terminal UE2 to the local home agent L-HA
21-1 does not include the local home address L-HoA2, the care-of
addresses CoA2-1 and CoA2-2, and the user address 2.
[0102] Accordingly, even when the local home agent L-HA 21-1
receives the provisional response signal (Session Progress) from
the mobile communications terminal UE2, the local home agent L-HA
21-1 neither creates nor transmits a list of candidate access
networks. (See FIG. 24B, step S13.) Further, even when receiving
the acknowledgement signal (PRACK) from the mobile communications
terminal UE1, the local home agent L-HA 21-1 does not select an
access network. (See FIG. 4B, step S19.)
[0103] Further, the local home agent L-HA 20-1 selects an access
network for the mobile communications terminal UE1 without
considering the state of the called-side network, taking into
account only QoS, an operator policy, etc., as well as the care-of
addresses CoA1-1 and CoA1-2 and the user preference 1 transmitted
from the mobile communications terminal UE1. (See FIG. 5B, steps
S22' and S23'.)
[0104] FIG. 6A and FIG. 6B shows an operational sequence at the
start of communications in the case where the mobile communications
terminal UE2 that is a called-side terminal directly returns a
response signal (OK) without a provisional response signal (Session
Progress).
[0105] In this case also, no network selection is performed on the
called network side. On the calling network side, the local home
agent L-HA 20-1, when receiving the response signal (OK), selects
an access network by taking into account only QoS, an operator
policy, etc., as well as the care-of addresses CoA1-1 and CoA1-2
and the user preference transmitted from the mobile communications
terminal UE1 (step S15).
Embodiment 3
[0106] Further, the embodiment shown in FIGS. 7A and 7B shows an
operational sequence at the start of communications in the case
where a calling-side terminal and network do not have a network
selecting function. Accordingly, the sequence of this embodiment is
different from the sequence shown in FIG. 4A and FIG. 4B as
follows.
[0107] The call originating request signal (Invite) from the mobile
communications terminal UE1 to the local home agent L-HA 20-1 does
not include the local home address L-HoA1, the care-of addresses
CoA1-1 and CoA1-2, and the user address.
[0108] The local home agent L-HA 20-1 does not select an access
network even when receiving the provisional response signal
(Session Progress) from the local home agent L-HA 21-1. (See FIG.
4A, step S15.)
[0109] The local home agent L-HA 21-1 selects an access network for
the mobile communications terminal UE2 without considering the
state of the calling-side network, taking into account only QoS, an
operator policy, etc., as well as the care-of addresses CoA2-1 and
CoA2-2 and the user preference 2 transmitted from the mobile
communications terminal UE2.
[0110] Further, FIG. 8A and FIG. 8B show an operational sequence at
the start of communications in the case where a calling-side
terminal does not support an acknowledgment signal (PRACK). In this
case also, no network selection is performed on the calling network
side. On the called network side, after transmitting a provisional
response signal (Session Progress) (step S14), the mobile
communications terminal UE2 further transmits a response signal
(OK) (step S15).
[0111] When receiving an acknowledgement signal (ACK) from the
mobile communications terminal UE1 (step S18), the local home agent
21-1 selects an access network, taking into account only QoS, an
operator policy, etc., as well as the care-of addresses CoA2-1 and
CoA2-2 and the user preference 2 transmitted from the mobile
communications terminal UE2 (step S19).
Embodiment 4
[0112] Next, as a further embodiment of the present invention, a
handover sequence in the case where a mobile communications
terminal UE in communication detects an occasion to switch access
networks is shown in FIG. 9. Here, the mobile communications
terminal UE may detect an occasion for handover when the mobile
communications terminal UE, which has been receiving a streaming
service by W-CDMA, has moved in a W-LAN service provision area or
when the optimum access network has changed as a result of a change
of service (from streaming to voice) in an environment where
multiple access networks are available.
[0113] When the mobile communications terminal UE1 in communication
via the access network 20b (step S100) detects a handover occasion
for switching to the access network 20a (step S30), the mobile
communications terminal UE1 includes the local home agent L-HoA
20-1, the care-of addresses CoA1-1 and CoA1-2, the user preference
1, and an access network selection request in a location
registration information update signal (Binding Update), and
transmits it to the local home agent L-HA 20-1 via the access
network 20b (step S31).
[0114] Receiving the above-described request from the mobile
communications terminal UE1, the local home agent L-HA 20-1, in
cooperation with the PDF 20-2, selects an optimum access network
for the mobile communications terminal UE1, taking into account
QoS, an operator policy, etc., as well as the care-of addresses
CoA1-1 and CoA1-2 and the user preference transmitted from the
mobile communications terminal UE1 (step S32). In this embodiment,
the access network 20a is selected.
[0115] The local home agent L-HA 20-1 includes the selection
information of the selected access network 20a in a response signal
(Binding Ack), and transmits it to the mobile communications
terminal UE1 (step S33).
[0116] Receiving the response signal (Binding Ack) from the local
home agent L-HA 20-1, the mobile communications terminal UE1
recognizes that the access network 20a has been selected, and
reserves radio resources for performing communications via the
access network 20a (step S34).
[0117] The mobile communications terminal UE1 notifies the local
home agent L-HA 20-1 of the reservation of radio resources through
a location registration information update signal (Binding Update)
(step S34). Receiving this location registration information update
signal, the local home agent L-HA 20-1 thereafter transfers user
data to the mobile communications terminal UE1 via the access
network 20a (step S200).
[0118] After completion of this handover, the mobile communications
terminal UE1 may notify a correspondent mobile communications
terminal UE of a change of the access network that it uses (Update)
(step S35), so that the correspondent mobile communications
terminal UE may perform handover in response to this notification
as a trigger.
[0119] Further, in the case where both networks have the function
of selecting an access network as shown in the embodiment shown in
FIG. 3, the local home agent L-HA 20-1 can acquire information on
the type of the access network that is being used by the network
where the correspondent exists through a notification in the call
originating and receiving sequence shown in FIG. 3 or the
above-described notification after handover. Accordingly, in this
case, the local home agent L-HA 20-1 can select an access network,
taking into account the type of the access network that is being
used by the network where the correspondent exists as well.
[0120] FIG. 10 shows a handover sequence in the case where a device
in the network detects an occasion. Here, the device in the network
may detect a handover occasion when a streaming service has been
provided to a mobile communications terminal UE through W-CDMA but
it has become possible to provide the service through W-LAN because
of a change in the resource conditions of the access network of
W-LAN.
[0121] When the local home agent L-HA 20-1, which is providing a
service to the mobile communications terminal UE1 via the access
network 20b, detects a handover occasion (step S40), the local home
agent L-HA 20-1 transmits a handover occasion notification signal
to the mobile communications terminal UE1 (step S41).
[0122] The operations of the mobile communications terminal UE1 and
the local home agent L-HA 20-1 after reception of the signal are
the same as described in the above-described embodiment of FIG.
9.
[0123] Here, in the above description of the embodiments, it is
assumed that the local home agent L-HA and the PDF are provided in
the visited network (VN). However, the effects due to application
of the present invention remain the same even when their functions
are provided in the home network HN.
[0124] Further, the embodiments are described on the assumption
that the local home agent L-HA and the PDF are independent devices.
However, the effects are the same even when their functions are
provided in an existing device (such as P-CSCF).
[0125] Further, the information communicated as candidate access
networks available to the mobile communications terminals UE1 and
UE2 is not explicitly shown in the above-described embodiments, but
the care-of addresses CoAs of all access networks (currently)
available to the mobile communications terminals UE1 and UE2 at
that point may be transmitted or only the care-of address of a
particular access network selected in accordance with a service or
a user preference may be transmitted. The effects produced by the
present invention remain the same whichever one of these manners is
applied.
[0126] Further, the above-described embodiments show the cases
where both calling and called sides are mobile communications, but
the effects of the present invention remain the same even if one of
them is a fixed network terminal or a server.
[0127] Further, the above-described embodiments show the cases
where SIP is used for a protocol, but the effects of the present
invention remain the same even if other protocols are applied.
Embodiment 5
[0128] In the above-described embodiments, all of the access
networks provided in the visited networks VNs are managed by the
same operator. In the below-described embodiment, multiple networks
(visited networks VNs) of different operators are connected to a
home network HN to which a user belongs, and each network includes
multiple access networks. In other words, access network options
for a user include those of different operators. In this case, from
a network of one operator, it is impossible to know the details of
the situation of a network of another operator. Accordingly, it is
difficult to determine an appropriate combination of access
networks only with the techniques described in the first through
fourth embodiments.
[0129] In the invention according to the following embodiment, when
multiple access networks are provided by multiple operators, a
terminal notifies a device in the network of the type of an
available access network and a user preference. Taking into
account, in addition to these information items, what service or
application a user has requested, whether it is in a wired network,
the resource conditions in a radio section, an operator policy,
etc., each device in the network can select a visited network VN
and an access network at the time of originating a call and the
time of receiving a call. Further, if both calling network side and
called network side have the above-described network selecting
function, devices in the network notify each other of candidates
for an access network to be selected or a selected access network.
As a result, it is possible to select an access network in a
network, which access network is suitable for the candidates for
the access network to be selected or the selected access network in
the network where the correspondent exists.
[0130] Further, the present invention is also applicable in the
case where an identifier is provided for each individual access
network and a visited network VN itself has its own mobility
control function with multiple access networks connected to the
visited network VN as its subordinates as GPRS of 3GPP. In this
case, a home network HN selects one of the visited networks VN
having access networks and the mobility control function, and the
VN identifies the access networks that it manages. This makes it
possible to select an optimum combination of access networks
between the calling side and the called side.
[0131] According to the present invention, it is possible to
implement the function of selecting an optimum access network at
the time of originating and receiving a call and during
communication based on various conditions as well as a user
preference in a communications network having multiple access
networks, and there is no fixation to the result of selection at
the time of location registration.
[0132] An embodiment of the present invention in the case of
applying SIP as a protocol in a mobile communications network is
shown below.
[0133] FIG. 11 is a configuration diagram of a mobile
communications network that implements the present invention. UE1
and UE2 are mobile communications devices that actually perform
communications in the present invention, and are assigned their
respective home addresses (HoAs) HoA1 and HoA2 by home networks
(HNs) to which they subscribe. HN1 and HN2 are mobile
communications service provision networks to which UE1 and UE2
subscribe, respectively. Further, visited networks VN 1-1 and VN
1-2 and visited networks VN 2-1 and VN 2-2 are networks that UE1
and UE2 visit. These visited networks VNs are managed by different
operators in this embodiment. Further, access networks AN 1-1-1 and
AN 1-1-2 are access means provided to UE1 by VN 1-1. AN 1-2-1 and
AN 1-2-2 are access means provided to UE1 by VN 1-2. AN 2-1-1 and
AN 2-1-2 are access means provided to UE2 by VN 2-1. AN 2-2-1 and
AN 2-2-2 are access means provided to UE2 by VN 2-2.
[0134] The access network may be a wide area network such as a
W-CDMA mobile communications network or a wireless LAN provided in
a hot spot manner. Alternatively, the access network may be a
network advantageous to real-time data such as voice data or a
network advantageous to non-real-time data. Various access networks
may be provided from various operators at various locations, and a
user may exist in one or more of them.
[0135] FIG. 12 shows a function configuration corresponding to a
user device (for example, UE1) in a disposition of functions for
implementing the present invention. The correspondent of this user
may be in a similar communications environment. A local home agent
L-HA, which is a function part newly provided by the present
invention, has the function of assigning a local home address L-HoA
to a mobile communications terminal UE that moves in a service
provision range and the function of selecting an optimum access
network based on the type of an available access network and a user
profile transmitted from UE, QoS, an operator policy, etc.
[0136] The user device or mobile communications device UE1 has the
function of performing communications based on multiple radio
systems and has the function of being assigned a care-of address
(CoA) for each corresponding radio system and the L-HoA of a
visited network VN where it exists and storing them. Further, UE
has the function of notifying L-HA, at the time of requesting to
originate a call and at the time of responding to a received call,
of a care-of address (CoA) corresponding to an available radio
system (access network) at that time, a user preference, L-HoA,
etc.
[0137] In FIG. 12, L-HA and PDF are shown as independent devices or
function parts, but their functions may be provided in an existing
device (for example, P-CSCF).
[0138] FIG. 13A and FIG. 13B show a procedure for acquiring L-HoA
and CoA and performing registration with S-CSCF by UE1. The same
procedure is followed with respect to UE2.
[0139] As shown in FIG. 13A, when UE1 moves in the service
provision area of a visited network VN and receives the radio wave
of AN 1-1 or AN 1-2, UE1 is assigned CoA by each access network
(CoA1-1 and CoA1-2) (S2).
[0140] UE1 registers HoA1 assigned thereto by the home network HN
and CoA1-1 assigned thereto by AN 1-1 with L-HA1 via AN 1-1
(S4).
[0141] When receiving the registration from UE1, L-HA1 refers to a
table it retains, and determines whether L-HoA corresponding to
HoA1 has been assigned. If L-HoA has not been assigned, L-HA1
assigns L-HoA1 to UE1, includes it in a response to the
registration, and transmits it to UE1.
[0142] UE1 registers HoA1 and CoA1-2 with L-HA1 via AN 1-2 in the
same procedure (S6).
[0143] Since L-HA1 has already assigned L-HoA1 to UE1, L-HA1 makes
only a response of registration completion to UE1.
[0144] As shown in FIG. 13B, upon completion of registration of all
acquired CoAs with L-HA1 and acquisition of L-HoA1, UE1 registers
L-HoA1 with S-CSCF in the home network HN to which it subscribes
(S8, S10).
[0145] By the above-described procedure, acquisition of L-HoA and
CoA and registration with S-CSCF by UE are completed.
[0146] In the procedure of FIGS. 13A and 13B, two binding updates
and two registration requests are made because there are two
available access networks. If the number of access networks is
different, binding updates (Binding Update) and registration
requests (Register) corresponding to that number are made. In
general, the procedure of FIG. 13A is an address registration
procedure for the address table of a router in mobile IP, and the
procedure of FIG. 13B is an address registration procedure for
originating and receiving a call in 3GPP SIP protocol. The same
addresses are registered in each procedure, but by performing them
separately as graphically illustrated, it is possible to make
preparations for the present invention without changing existing
protocols.
[0147] FIG. 14A and FIG. 14B show an operational sequence at the
start of communications in the case where a communication request
has been transmitted from UE1 to UE2 when a home network HN
statically selects a visited network VN and the visited network VN
dynamically selects an access network AN. A description is given
below of the meanings of statically and dynamically. FIG. 14A shows
an operational sequence on the calling side (UE1 side), an FIG. 14B
shows an operational sequence on the called side (UE2 side).
[0148] In the graphically illustrated case, six signals are
exchanged between UE1 and UE2. They are (1) a call originating
request (Invite) by UE1, (2) 183 Session Progress by UE2, (3) PRACK
by UE1, (4) 200-OK (such as PRACK) by UE2, (5) 200-OK (Invite) by
UE2, and (6) ACK by UE1.
[0149] UE1 includes HoA1, a user preference 1, a service type, and
a QoS request in a call originating request signal (Invite), and
transmits it to VN 1-1 (L-HA1-1) via AN 1-1-1 (S10). Here, L-HA
determines from which UE the received call originating request
signal has come by using HoA1. Further, the user preference 1 is
information for notifying L-HA1-1 on what basis the user of UE1
wishes to have network selection performed (for example, with
priority on communications speed, priority on communications cost,
etc.).
[0150] Receiving the call originating request signal (Invite) from
UE1, VN 1-1 (L-HA1-1) stores therein L-HoA1-1, CoA1-1-1, CoA1-1-2,
and the user preference 1, and issues a call originating request
signal to UE2 (S12). In the graphically illustrated case, the call
originating request signal is transmitted to VN-1 via AN 1-1-1.
However, this selection of an access network and a visited network
VN is provisional and subject to change after progress in the
subsequent procedure.
[0151] As shown in step S14 of FIG. 14B, HN2, which is a home
network HN on the called side (UE2 side), selects a visited network
NW suitable for the requested service, and transmits the call
originating request signal (Invite) to UE2 via the selected visited
network VN (VN 2-1 in this case). In this embodiment, this visited
network VN selected by HN2 is not to be changed even after progress
in the subsequent procedure. In other words, this selection is not
provisional. Which one of multiple visited networks VNs is selected
is determined based on a predetermined criterion independent of the
conditions of communications of UE2. "Statically determined" means
being thus determined by HN2 independent of the conditions of
communications of UE2. On the other hand, VN 2-1 selected by HN2
provisionally selects one of its subordinates access networks, and
communicates with UE2 through it. In the graphically illustrated
case, AN 2-1-1 is provisionally selected.
[0152] Receiving the call originating request signal (Invite), UE2
includes L-HoA2, CoA2-1-1, CoA2-1-2, and a user preference 2 in a
provisional response signal (183 Session Progress), and transmits
the provisional response signal to VN 2-1 (L-HA2-1) via AN 2-1-1
(S16). Here, the contents of the transmission from UE2 to VN 2-1
(L-HA2-1) are processed the same as the contents of the
above-described transmission from UE1 to L-HA1-1.
[0153] Receiving the provisional response signal (183 Session
Progress) from UE2, VN 2-1 (L-HA2-1) stores therein L-HoA2,
CoA2-1-1, CoA2-1-2, and the user preference 2 from UE2. Further, VN
2-1, in cooperation with PDF2-1 in VN 2-1, creates a list of access
networks ANs providing services to UE2 (a list of ANs arranged in
order suitable for this communication), and retains it in its
storage means. VN 2-1 issues the contents of the list and a
provisional response signal (183 Session Progress) to UE1 (S18). In
creating the list, QoS, an operator policy, etc., as well as
CoA2-1-1, CoA2-1-2, and the user preference 2 transmitted from UE2
are considered. The contents of the information transmitted as
candidate access networks available to UE2 may vary. For example,
CoAs of all access networks ANs available to UE2 at that time may
be transmitted, or only the care-of address of a particular access
network AN selected in accordance with a service or a user
preference may be transmitted, or other information may be
transmitted.
[0154] As shown in S20 of FIG. 14A, HN1, which is the home network
of UE1, selects a visited network VN suitable for the requested
service. This selection is also statically performed. That is, the
visited network VN is determined in accordance with a predetermined
condition. HN1 includes the selected visited network VN (VN 1-2 in
this case) in the provisional response signal (183 Session
Progress), and transmits it to UE1 through VN 1-1 from which the
call originating request from UE1 has been received. That is,
information indicating the finally determined visited network VN
(VN 1-2 in the graphically illustrated case) is reported to UE1
through provisionally determined VN 1-1 and AN 1-1-1.
[0155] Receiving the provisional response signal (183 Session
Progress), UE1 includes L-HoA1, CoA1-2-1, CoA1-2-2, the user
preference 1, and AN 1-2 in an acknowledgement signal (PRACK), and
transmits the acknowledgement signal to VN 1-2 (L-HA1-2) (S22).
Here, the contents of the transmission from UE2 to VN 2-1 (L-HA2)
are the same as the contents of the above-described transmission
from UE1 to L-HA1-1.
[0156] As shown in S24, receiving the acknowledgement signal
(PRACK) from UE1, VN 1-2 (L-HA1-2), in cooperation with PDF1-2 in
VN 1-2, creates a list of access networks ANs providing services to
UE1 (a list of ANs arranged in order suitable for this
communication). The list is created by taking into account QoS, an
operator policy, etc., as well as CoA1-2-1, CoA1-2-2, and the user
preference 1 transmitted from UE1. L-HA1-2 includes the created
access network list in an acknowledgement signal (PRACK), and
transmits it to VN 2-1 (L-HA2-1).
[0157] As shown in S26 of FIG. 14B, receiving the acknowledgement
signal (PRACK) from UE1, VN 2-1 (L-HA2-1), in cooperation with
PDF2-1 in VN 2-1, selects an optimum access network AN for UE2 (AN
2-1-2 is selected in this embodiment), taking into account QoS, an
operator policy, etc., as well as the access network AN list
transmitted from UE1 and CoA2-1-1, CoA2-1-2, and the user
preference 2 transmitted from UE2. VN 2-1 (L-HA2-1) includes the
selected access network in an acknowledgement signal (PRACK), and
transmits it to UE2. The transmission is performed through AN
2-1-1, which is being used provisionally at the moment, but
thereafter, UE2 is to access AN 2-1-2 following the contents of the
determination. Thus, the selection of an access network is not a
static selection but is "dynamically" performed based on the actual
situation of communications and the idea of UE.
[0158] As shown in S28, receiving the acknowledgement signal
(PRACK) from L-HA2, UE2 recognizes that AN 2-2 has been selected.
UE2 reserves radio resources for performing communications via AN
2-2. UE2 includes the fact that the selected AN is. AN 2-2 in a
response signal (200 OK) to PRACK, and returns it to UE1. Further,
UE2 returns a response signal (200 OK) to Invite to UE1.
[0159] As shown in S30 of FIG. 14A, receiving the response signal
(200 OK) to PRACK from UE2, VN 1-2 (L-HA1-2), in cooperation with
PDF1-2 in VN 1-2, selects an optimum access network AN for UE1 (AN
1-2-2 is selected in this embodiment). In this selection, QoS, an
operator policy, etc., as well as the list of the access network AN
selection result transmitted from UE2 and CoA1-2-1, CoA1-2-2, and
the user preference 1 transmitted from UE1 are considered.
[0160] As shown in S32, VN 1-2 (L-HA1-2) includes the selected
access network AN in the response signal (200 OK) to PRACK, and
transmits it to UE1. Receiving the response signal (200 OK) to
PRACK from L-HA1, UE1 recognizes that AN 1-2-2 has been selected,
and reserves radio resources for performing communications via AN
1-2-2.
[0161] As shown in S34, UE1 includes information on the type of the
selected access network AN in an acknowledgement signal (ACK)
responsive to the response signal (200 OK) to Invite, and transmits
it to UE2. The information on the type of the selected access
network AN may be included in ACK and transmitted to UE2 by L-HA1,
which has actually performed the selection.
[0162] As shown in S36 of FIG. 14B, the operational sequence at the
start of communications is completed by reception of the
acknowledgement signal (ACK) responsive to 200 OK (Invite) from UE1
by UE2. Thereafter, UE1 and UE2 can perform high-quality
communications through the access networks appropriately selected
between them.
[0163] As shown in S30 of FIG. 14A, the visited network VN 1-2
statically selected by the home network HN selects the appropriate
access network AN 1-2-2 after receiving 200-OK (PRACK, AN 2-1-2).
It should be noted, however, that VN 1-2 may select AN 1-2-2 at any
time after the point of creation of the candidate AN list of S24.
However, it is preferable to time the selection of AN as
graphically illustrated in terms of simplifying the operational
procedure by performing processing such as receiving and processing
a signal and transmitting the signal in a unified manner in the
entire system.
Embodiment 6
[0164] FIG. 15A and FIG. 15B show an operational sequence at the
start of communications in the case where a home network HN
dynamically selects a visited network VN and the visited network VN
also dynamically selects an access network AN. The dynamic
selection of the access network by the selected visited network VN
is common to the technique shown in FIGS. 14A and 14B and the
technique shown in FIGS. 15A and 15B. However, the technique shown
in FIGS. 15A and 15B, where the home network HN also dynamically
selects the visited network VN, is different in that point from the
technique shown in FIGS. 14A and 14B, which statically selects
it.
[0165] As shown in S10 of FIG. 15A, UE1 transmits a call
originating request signal (Invite) to UE2. As shown in FIG. 15B,
the call originating request signal from UE1 is transmitted to all
visited networks VN 2-1 and VN 2-2 available to UE2.
[0166] As shown in parallel in S12 and S14, receiving the call
originating signal (Invite), UE2 includes necessary information in
a provisional response signal (183 Session Progress) the same as in
the processing of S16 shown in FIG. 14B, and transmits it to each
of VN 2-1 and VN 2-2. Receiving the provisional response signal
(183 Session Progress) from UE2, VN 2-1 and VN 2-2 each create a
list of candidate ANs providing services to UE2. The candidate AN
list with respect to each VN is transmitted from HN2 to UE1 by the
provisional response signal (183 Session Progress).
[0167] As shown in S16 and S18 of FIG. 15A, a list of candidate ANs
is created in each of VN 1-1 and VN 1-2 on the UE1 side. In this
case, HN1 transmits 183 Session Progress through not only the
visited network VN through which UE1 has made the call originating
request but also all visited networks VNs whose locations are
registered. Receiving PRACK responsive to 183 Session Progress from
UE1, each of VN 1-1 and VN 1-2 creates a list of candidate ANs in
its own network. Receiving these lists, HN1 creates a list of all
the candidate ANs for UE1.
[0168] As shown in S20 of FIG. 15B, HN2 selects an optimum visited
network VN for UE2 (VN 2-1 is selected in this embodiment), taking
into account QoS, an operator policy, etc., as well as the
candidate AN list for UE1 included in PRACK received from HN1 and
the candidate AN list for UE2 and the user preference 2 that it
retains. The selected VN selects an appropriate AN (AN 2-1-2 is
selected in the graphically illustrated case), and information on
the selected VN and AN is transmitted to UE2.
[0169] As shown in S22, recognizing the contents of the
transmission, UE2 reserves radio resources for performing
communications via AN 2-1-2. UE2 includes the fact that the
selected access network AN is AN2-1-2 in a response signal (200 OK)
to PRACK, and returns it to UE1. Further, UE2 returns a response
signal (200 OK) to Invite to UE1.
[0170] As shown in S24 of FIG. 15A, HN1 selects an optimum visited
network VN for UE1 (VN 1-2 is selected in this embodiment), taking
into account QoS, an operator policy, etc., as well as the
candidate AN list for UE2 included in 200 OK (PRACK) received from
HN2 and the candidate AN list for UE1 and the user preference 1
that it retains. The selected VN selects an appropriate AN (AN
1-2-2 is selected in the graphically illustrated case), and
information on the selected VN and AN is transmitted to UE1.
Recognizing the contents of the transmission, UE1 reserves radio
resources for performing communications via AN 1-2-2.
[0171] As shown in S26, UE1 includes information on the type of the
selected access network AN in an acknowledgement signal (ACK)
responsive to the response signal (200 OK) to Invite, and transmits
it to UE2.
[0172] As shown in S28 of FIG. 15B, the operational sequence at the
start of communications is completed by reception of the
acknowledgement signal (ACK) responsive to 200 OK (Invite) from UE1
by UE2. In this embodiment, a visited network VN is not statically
selected, but is dynamically selected in accordance with the
intention of UE. Accordingly, UE1 and UE2 can perform
communications with higher quality through the access networks
selected more appropriately between them.
Embodiment 7
[0173] FIG. 16A and FIG. 16B show an operational sequence in the
case where a home network HN statically selects a visited network
VN and an access network AN. In the fifth and sixth embodiments, HN
merely selects VN, and VN is in charge of selecting AN. In this
embodiment, HN also selects AN. Further, VN and AN are statically
selected. More specifically, HN2 determines not only VN but also an
access network AN upon receiving Invite from UE1, and the call
originating request signal (Invite) is transmitted to UE2 through
the determined VN and AN (VN 2-1 and AN 2-1-2 in this case).
Further, HN1 determines not only VN but also AN upon receiving 183
Session Progress from UE2, and the contents of the determined VN
and AN (VN 1-2 and AN 2-1-2 in this case) are transmitted to UE1 by
the provisional response signal (183 Session Progress).
[0174] In this embodiment, AN is not dynamically selected.
Accordingly, the procedure for creating a list of candidate ANs is
unnecessary, so that it is possible to simplify a procedure.
Embodiment 8
[0175] FIGS. 17A and 17B show an operational sequence at the start
of communications in the case where a home network HN dynamically
selects a visited network VN and an access network AN. The fact
that HN selects both VN and AN is common to the seventh embodiment
and this embodiment, but this embodiment is different from the
seventh embodiment in that that selection is dynamically performed.
The specific operational sequence is the same as the one shown in
FIG. 15A and FIG. 15B except that HN selects VN and AN.
Embodiment 9
[0176] FIG. 18A and FIG. 18B show an operational sequence at the
start of communications in the case where a home network HN
statically selects only a visited network VN and the visited
network VN statically selects an access network AN. This sequence
is similar to the sequence shown in FIG. 14A and FIG. 14B, but is
different therefrom in that VN selected by HN selects AN upon
receiving Invite or 183 Session Progress. In this embodiment, AN is
not dynamically selected. Accordingly, the procedure for creating a
list of candidate ANs is unnecessary, so that it is possible to
simplify a procedure.
[0177] In the above-described embodiments, it is assumed that both
calling side and called side are mobile communications networks,
but a correspondent may be a fixed network terminal or a server.
Further, in the above-described embodiments, a description is given
of the cases where SIP is used for a protocol. However, other
protocols may also be used.
Embodiment 10
[0178] By the way, an operator provides services in various forms.
In some cases, there may be an environment where a visited network
VN of the operator has one or more of its subordinate access
networks managed by a single management part and the visited
network VN is capable of communicating directly with the management
part but cannot directly distinguish the one or more of the access
networks under the management part. For example, according to 3GPP,
it is possible to accommodate different types of access networks
(UTRAN and GERAN) under a common core network (GPRS). In this case,
according to the conventional access network selection method, it
is impossible to select subordinate UTRAN or GERAN connected to
GPRS although it is possible to select GPRS itself, for GPRS is
regarded as one access network. That is, since there is a specific
mobility management function between one visited network VN and
multiple access networks, these access networks are seen as one
from the visited network VN, so that the visited network VN cannot
directly select its subordinate access networks. The tenth
embodiment of the present invention can cope with such a
problem.
[0179] FIG. 19 shows a diagram of a network configuration where a
specific mobility management function part (Mobility Management:
MM) is provided between one visited network VN and multiple access
networks. In this case, irrespective of which one of AN 1-1 and AN
1-2 UE1 is using, the visited network VN transmits user data to the
Mobility Management (MM), and the Mobility Management transfers the
data to AN that is being used by UE1.
[0180] FIG. 20 shows a procedure for acquisition of L-HoA and CoA
and registration with S-CSCF by UE, taking the case of UE1 as an
example. As graphically illustrated, when UE1 enters the service
provision area of the visited network VN and receives the radio
wave of AN 1-1 or AN 1-2, UE1 acquires CoA1-1 from MM via either AN
(AN 1-1 in this embodiment) (S2). In FIG. 13A and FIG. 13B, the
care-of addresses CoA1 and CoA2 are assigned to UE by AN 1-1 and AN
1-2 subordinate to the visited network VN, respectively, and are
registered with the network via the respective access networks ANs.
In this embodiment, the mobility management function part MM
assigns the care-of address CoA1-1, but no such care-of address is
assigned to an access network. That is, MM assigns (provides)
CoA1-1 common to AN 1-1 and AN 1-2 to UE. Registration with the
network from UE is performed through only one of ANs.
[0181] UE1 registers HoA1 assigned by a home network HN and CoA1-1
assigned by MM with L-HA1 via AN 1-1 (S4).
[0182] Upon receiving the registration from UE1, L-HA1 refers to a
table that it retains, and determines whether L-HoA corresponding
to HoA1 has been assigned. If L-HoA has not been assigned, L-HA1
assigns L-HoA1 to UE1, includes it in a response to the
registration, and transmits it to UE1.
[0183] Upon completion of registration of the acquired CoA with
L-HA1 and acquisition of L-HoA1, UE1 registers L-HoA1 with S-CSCF
in the home network HN to which it subscribes (S6). Identifiers for
AN identification AN 1-1 and AN 1-2 are added to the parameters of
this registration from UE (Register).
[0184] By the above-described procedure, acquisition of L-HoA and
CoA and registration with S-CSCF by UE are completed. Thereby, even
when a network structure such as FIG. 19 is used, information
distinguishing between all access networks available to UE is
stored in the home network HN and the visited network VN. As a
result, it is possible to appropriately select a combination of
access networks suitable for the communications of UE1 and UE2 with
the same procedure as the procedure described in each of the
above-described embodiments.
[0185] As described above, a visited network VN is statically or
dynamically selected by a home network HN. An access network AN may
be statically or dynamically selected by the visited network VN or
may be statically or dynamically selected by the home network HN.
Static selection is preferred in terms of prompt determination of
the access network AN and/or the visited network VN. Dynamic
selection is preferred in terms of selecting an access network AN
and/or a visited network VN that truly suits the communications
conditions of a user. If the visited network VN does not wish to
transmit information on its subordinate access network AN to the
home network HN, it is preferable that the visited network VN
select an access network AN. In terms of unifying management of the
access network AN and the visited network VN, it is preferable that
the home network HN select them.
[0186] Further, according to embodiments of the present invention,
the following configurations may also be provided.
[0187] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
transmitting a signal of a call originating request from a
calling-side terminal making the call originating request;
notifying a device in a called-side network of an identifier
corresponding to a currently available access network and a user
preference from a called-side terminal having received the call
originating request; making a list of candidates for an access
network to be assigned to the called-side terminal in response to
reception of the notification signal as a trigger, and transmitting
the list from the device in the called-side network to the
calling-side terminal; transmitting an acknowledgement signal
responsive to a notification signal from the device in the
called-side network, from the calling-side terminal; and
determining the access network to be assigned to the called-side
terminal in response to reception of the acknowledgement signal
from the calling-side terminal as a trigger, and notifying the
called-side terminal of the determined access network by the device
in the called-side network (Configuration 1).
[0188] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
transmitting a signal of a call originating request from a
calling-side terminal making the call originating request;
notifying a device in a called-side network of an identifier
corresponding to a currently available access network and a user
preference from a called-side terminal having received the call
originating request; making a list of candidates for an access
network to be assigned to the called-side terminal based on a
predetermined condition in response to reception of a notification
signal from the called-side terminal as a trigger, and transmitting
the list from the device in the called-side network to the
calling-side terminal; further transmitting a response signal to
the signal of the call originating request, from the called-side
terminal; transmitting an acknowledgement signal responsive to the
response signal from the called-side terminal, from the
calling-side terminal; and determining the access network to be
assigned to the called-side terminal based on a predetermined
condition in response to reception of the acknowledgement signal,
and notifying the called-side terminal of the determined access
network by the device in the called-side network (Configuration
2).
[0189] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
detecting availability of an access network other than a currently
used access network by a terminal in communication; notifying a
device in the network of an identifier corresponding to the
currently available access network, a user preference, and an
access network selection request by the terminal having performed
the detection; and determining an access network to be assigned to
the terminal in response to reception of a notification signal from
the terminal as a trigger, and notifying the terminal of the
determined access network by the device in the network
(Configuration 3).
[0190] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network having multiple access networks, including the steps of:
detecting availability of an access network other than a currently
used access network to a terminal in communication, and notifying
the terminal of the availability by a device in the network;
notifying the device in the network of an identifier corresponding
to the currently available access network, a user preference, and
an access network selection request from the terminal having
received the notification signal; and determining an access network
to be assigned to the terminal in response to reception of a
notification signal from the terminal as a trigger, and notifying
the terminal of the determined access network by the device in the
network (Configuration 4).
[0191] Additionally, the access network selection method as set
forth above in Configuration 3 or 4 may include the step of
notifying a correspondent of the access network selection result
(Configuration 5).
[0192] Additionally, in the access network selection method as set
forth above in Configuration 5, a terminal having received the
notification may select an access network (Configuration 6).
[0193] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network where multiple operators have respective networks and each
of the networks includes multiple access networks, including the
steps of: transmitting a signal of a call originating request
including a service type to a called-side terminal by a
calling-side terminal; selecting a visited network available to the
called-side terminal among the networks managed by the different
operators in accordance with the service type, including the
selection result in the call originating request, and transmitting
the call originating request to the called-side terminal by a home
network of the called-side terminal having received the call
originating request; notifying a device in the called-side visited
network of an identifier of an available one or more of the access
networks in the selected visited network and a user preference by
the called-side terminal having received the call originating
request; transmitting a list of candidates for an access network to
be assigned to the called-side terminal to a device in a
calling-side network by the device in the called-side visited
network; selecting one of multiple visited networks available to
the calling-side terminal in accordance with the service type and
notifying the calling-side terminal of the selection result by a
home network of the calling-side terminal having received the list;
notifying a device in the calling-side visited network of an
identifier of an available one or more of the access networks in
the selected one of the visited networks and a user preference by
the calling-side terminal having received the selection result;
determining an access network to be assigned to the calling-side
terminal and notifying a called-side network of the determined
access network by the device in the calling-side visited network;
determining the access network to be assigned to the called-side
terminal and notifying the called-side terminal of the determined
access network by the device in the called-side visited network;
notifying the calling-side terminal of the access network assigned
to the called-side terminal by one of the called-side terminal and
the device in the called-side visited network; determining the
access network to be assigned to the calling-side terminal and
notifying the calling-side terminal of the determined access
network by the device in the calling-side visited network; and
notifying the called-side terminal of a type of the access network
assigned to the calling-side terminal by one of the calling-side
terminal and the device in the calling-side visited network
(Configuration 7).
[0194] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network where multiple operators have respective networks and each
of the networks includes multiple access networks, including the
steps of: transmitting a signal of a call originating request
including a service type to a called-side terminal by a
calling-side terminal; transmitting the signal of the call
originating request to the called-side terminal from multiple
visited networks available to the called-side terminal among the
networks managed by the different operators; notifying each of
devices in the corresponding called-side visited networks of an
identifier of an available one or more of the access networks with
respect to each of the visited networks and a user preference by
the called-side terminal having received the call originating
request; transmitting a list of candidates for an access network to
be assigned to the called-side terminal to a home network of the
called-side terminal by each of the devices in the called-side
visited networks; creating a list of multiple access networks
available to the called-side terminal based on the lists and
transmitting the list to a home network of the calling-side
terminal by the home network of the called-side terminal;
transmitting the list to the calling-side terminal through multiple
visited networks available to the calling-side terminal by the home
network of the calling-side terminal having received the list;
notifying each of devices in the corresponding calling-side visited
networks of an identifier of an available one or more of the access
networks with respect to each of the visited networks and a user
preference by the calling-side terminal having received the list;
transmitting a list of candidates for an access network to be
assigned to the calling-side terminal to the home network of the
calling-side terminal by each of the devices in the calling-side
visited networks; creating a list of multiple access networks
available to the calling-side terminal based on the lists and
transmitting the list to the home network of the called-side
terminal by the home network of the calling-side terminal;
selecting a visited network to be assigned to the called-side
terminal and notifying the selected visited network of the
selection by the home network of the called-side terminal;
determining the access network to be assigned to the called-side
terminal and notifying the called-side terminal of the determined
access network by the device in the called-side visited network;
notifying the calling-side terminal of the access network assigned
to the called-side terminal by one of the called-side terminal and
the device in the called-side visited network; selecting a visited
network to be assigned to the calling-side terminal and notifying
the selected visited network of the selection by the home network
of the calling-side terminal; determining the access network to be
assigned to the calling-side terminal and notifying the
calling-side terminal of the determined access network by the
device in the calling-side visited network; and notifying the
called-side terminal of a type of the access network assigned to
the calling-side terminal by one of the calling-side terminal and
the device in the calling-side visited network (Configuration
8).
[0195] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network where multiple operators have respective networks and each
of the networks includes multiple access networks, including the
steps of: transmitting a signal of a call originating request
including a service type to a called-side terminal by a
calling-side terminal; selecting the network of one of the
operators and one of the access networks thereof in accordance with
the service type, including the selection result in the call
originating request, and transmitting the call originating request
to the called-side terminal by a home network of the called-side
terminal having received the call originating request; transmitting
a response signal to the calling-side terminal by the called-side
terminal having received the call originating request; selecting
the network of one of the operators and one of the access networks
thereof in accordance with the service type and notifying the
calling-side terminal of the selection result by a home network of
the calling-side terminal having received the response signal;
notifying the calling-side terminal of a type of the access network
assigned to the called-side terminal by one of the called-side
terminal and a device in a called-side network; and notifying the
called-side terminal of a type of the access network assigned to
the calling-side terminal by one of the calling-side terminal and a
device in a calling-side network (Configuration 9).
[0196] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network where multiple operators have respective networks and each
of the networks includes multiple access networks, including the
steps of: transmitting a signal of a call originating request
including a service type to a called-side terminal by a
calling-side terminal; transmitting the signal of the call
originating request to the called-side terminal through one or more
visited networks available to the called-side terminal among the
networks managed by the different operators by a home network of
the called-side terminal having received the call originating
request; notifying each of devices in the corresponding called-side
visited networks of an identifier of an available one or more of
the access networks with respect to each of the visited networks
and a user preference by the called-side terminal having received
the call originating request; transmitting a list of candidates for
an access network to be assigned to the called-side terminal to the
home network of the called-side terminal by each of the devices in
the called-side visited networks; creating a list of multiple
access networks available to the called-side terminal based on the
lists and transmitting the list to a home network of the
calling-side terminal by the home network of the called-side
terminal; transmitting the list to the calling-side terminal
through multiple visited networks available to the calling-side
terminal by the home network of the calling-side terminal;
notifying each of devices in the corresponding calling-side visited
networks of an identifier of an available one or more of the access
networks with respect to each of the visited networks and a user
preference by the calling-side terminal; transmitting a list of
candidates for an access network to be assigned to the calling-side
terminal to the home network of the calling-side terminal by each
of the devices in the calling-side visited networks; creating a
list of multiple access networks available to the calling-side
terminal based on the lists and transmitting the list to the home
network of the called-side terminal by the home network of the
calling-side terminal; selecting a visited network and the access
network to be assigned to the called-side terminal and notifying
the called-side terminal of the selected visited network and access
network by the home network of the called-side terminal; notifying
the calling-side terminal of the access network assigned to the
called-side terminal by one of the called-side terminal and the
device in the called-side visited network; selecting a visited
network and the access network to be assigned to the calling-side
terminal and notifying the calling-side terminal of the selected
visited network and access network by the home network of the
calling-side terminal; and notifying the called-side terminal of
the access network assigned to the calling-side terminal by one of
the calling-side terminal and the device in the calling-side
visited network (Configuration 10).
[0197] According to one embodiment of the present invention, there
is provided an access network selection method in a communications
network where multiple operators have respective networks and each
of the networks includes multiple access networks, including the
steps of: transmitting a signal of a call originating request
including a service type to a called-side terminal by a
calling-side terminal; selecting one of the networks managed by the
different operators as a visited network in accordance with the
service type and notifying a device in the called-side visited
network of the selection result by a home network of the
called-side terminal having received the signal of the call
originating request; selecting an access network in accordance with
the service type, including the selection result in the call
originating request, and transmitting the call originating request
to the called-side terminal by the device in the called-side
visited network; transmitting a response signal to the calling-side
terminal by the called-side terminal having received the signal of
the call originating request; selecting one of the networks managed
by the different operators as a visited network in accordance with
the service type and notifying a device in the calling-side visited
network of the selection result by a home network of the
calling-side terminal having received the response signal;
selecting an access network in accordance with the service type and
notifying the calling-side terminal of the selection result by the
device in the calling-side visited network; notifying the
calling-side terminal of a type of the access network assigned to
the called-side terminal by one of the called-side terminal and the
device in the called-side visited network; and notifying the
called-side terminal of a type of the access network assigned to
the calling-side terminal by one of the calling-side terminal and
the device in the calling-side visited network (Configuration
11).
[0198] A description is given above of preferred embodiments of the
present invention. However, the present invention is not limited to
the specifically disclosed embodiments, and variations and
modifications may be made without departing from the scope of the
present invention. For convenience of description, the present
invention is divided into several embodiments, of which a
description has been given. However, the separation of the
embodiments is not essential to the present invention, and one or
more of the embodiments may be used as required.
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